The present invention relates to an improved apparatus and method for placing an anchor within a concrete structure and forming a void around the anchor. It is also concerned with an improved method for forming the apparatus wherein a thin shell with hinged sections is formed with a polymeric material.
The oldest and most common void formers employ solid urethane blocks which have an undersurface of a generally arcuate configuration and a slot formed therein and extending into the undersurface for releasable receipt of the anchor to be positioned. The blocks carry protrusions which extend across the slot to releasably engage the anchor. In use, the block is plastically deformed to engage and disengage the anchor. A recent variation of such an anchor wherein the slot is narrowed and defines a passage complimental with the shape of the anchor is seen in U.S. Pat. No. 6,082,700. Earlier examples are found in U.S. Pat. No. 4,383,674, 4,821,994, 5,535,979 and 5,651,911.
It is also well known in the art to provide hollow void formers for positioning anchors wherein the void formers have a smooth arcuate undersurface with a slot formed therein for receipt of the anchor. Such void formers, however, are relatively rigid and require some type of separate retaining element to secure the anchor within the slot. An example of such a void former can be found in U.S. Pat. No. 5,094,047.
A disadvantage of the solid block prior art void formers is that they are relatively expensive and have a surface of little lubricity. A disadvantage of the prior art hollow void formers is that they too are relatively expensive and require a separate anchor retaining element.
In its broadest aspects, the apparatus of the invention comprises a hollow body having first and second sections hinged together for movement between a closed condition engageable around an anchor received therebetween and an open condition in which the sections are separated to release an anchor received therebetween. A latch is disposed between the sections to releasably secure them in the closed condition. A passage for an anchor is defined between the first and second sections.
The method of embedding a lifting anchor in a concrete structure according to the invention comprises providing a polymeric hollow body having a first and second sections hinged together at their upper portions for movement between a closed condition engageable around an anchor received therebetween and an open condition in which the sections are separated to release an anchor received therebetween. The sections define a passage therebetween for receipt and retention of a lifting anchor and are provided with a latch to selectively secure the sections together. In the method, the sections are moved apart to receive the anchor and then moved together to secure the anchor in place. As so conditioned, the void former is cast in place within a concrete structure and, ultimately, removed from the structure by spreading the first and second sections apart and releasing them from the anchor.
The method of forming the void former comprises providing a mold for injection molding a polymeric material into a body having first and second sections joined by a bridge therebetween and then removing the body from the mold and hinging the sections relative to one another through bending of the bridge, before the polymer is fully cured. In the preferred embodiment, the sections are molded in a condition where the first and second sections are separated and hingedly connected by the bridge. This enables a protruding latching device to be formed between the sections. After removal of the body from the form, and before the polymer has fully cured, the bridge is bent to alter its molecular structure and facilitate it for repeated usage as a hinge.
A principal object of the invention is to provide an improved void former of the type described comprised of a hollow polymeric shell having sections which are hingedly interconnected and provided with a latch to reasonably secure them in complemental engagement.
Another object of the invention is to provide a method of forming such a void former and the hinge and latch structure thereof as a unitary monolithic structure.
Still another and more specific object of the invention is to provide a void former comprised of hingedly interconnected hollow elements formed of polymeric material having a lubricious surface.
Still another and more general object of the invention is to provide such a void former which is relatively inexpensive to manufacture and has increased longevity, as compared to prior art void formers.
Yet another object of the invention is to provide such a void former which is easier to use than prior art void formers both in its installation and removal.
These and other objects will become more apparent from the accompanying drawings and the following detail description.